Major Source of Reclaimed Hardwood
One of the major sources for hardwood to make reclaimed hardwood flooring is from buildings that are torn down or have major re-fitting. Either job produces a lot of unwanted hardwood. This wood can be reused; it is called reclaimed structural hardwood.
Types of Reclaimed Structural Hardwood
The wood can be used for a number of uses in a house and the previous function largely determines the type of markings that you can expect to find on the hardwood. For example wood that was used under rafters (purlins) tends to have nail, screw or bolt holes where the wood was attached. This will show up when it is made into reclaimed hardwood flooring.
Hardwood that was used as floor joists has marks at the edges where it was attached. Wood formerly used for truss chords has bolt holes, notches and mortice join holes. Ridge boards make hardwood flooring that has nail holes along the surface where rafters were formerly attached.
Backsawn vs. Quartersawn
Moreover, hardwood used in the building of a house is backsawn rather than quartersawn. This can cause gum lines and discoloration. Quartersawn hardwood has a more uniform look and far less markings.
It is worth doing due diligence before committing to buying reclaimed hardwood flooring to make sure you know where the wood came from. This will give you many clues about the markings to expect on the wood.